As discussed in Japanese Patent Application Publication No. 2001-102090, a film-packaged cell in which a power-generating element (produced by laminating a positive electrode plate and a negative electrode plate through a separator) is housed in a flat rectangular packaging body together with an electrolytic solution has been known, the film-packaged cell being sealed along the four edges of the packaging body in a state where terminals are led out through one side thereof. In the manufacturing process for this kind of film-packaged cell, the electrolytic solution is ordinarily injected into a bag-shaped body in which three edges excluding the upper edge of the packaging body are sealed in an orientation where the terminals are protruding laterally, the electrolyte being injected from the side of the opening upper edge. The unsealed upper edge is sealed after the injection thereby producing a film-packaged cell.
Though the electrolytic solution injected from the side of the opening upper edge of the bag-shaped body is to flow downwardly while penetrating through gaps between the bag-shaped body and the power-generating element housed therein, it becomes difficult to flow downwardly in the vicinity of the one side through which the terminals are led out, because an elongated portion etc. for connecting the terminals to the positive and negative electrode plates exists there so as to narrow the gap and reduce the cross sectional area of the flow passage as compared with the vicinity of the opposite side through which terminals are not led out. Hence there is a fear that the electrolytic solution leaks out during the injection of the electrolytic solution from the upper edge in the vicinity of the one edge through which the terminals are led out.
If the electrolytic solution leaks out, there may arise a fear that the injection of the electrolytic solution is not enough. Additionally, once the electrolytic solution adheres to the terminals or the packaging body, a fear of deterioration in quality may arise; for example, defects in welding may occur when producing an assembled battery.